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ArcPy and ArcGIS – Geospatial Analysis with Python by Silas Toms

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Definition queries

An important property of Layer objects is the ability to dynamically set definition queries. A definition query is a SQL statement where clause that limits the data available for display, query, or other data operations (buffers, intersections, etc.) to only the rows that match the where clause. Definition queries could be set in an MXD by opening a layer's properties menu and using the Definition Query tab, but here we are concerned with how to add them programmatically. Following is an example of how to do this:

layersList = arcpy.mapping.ListLayers(mxdObject,"",dataFrame)
busStops = layersList[0]
busStops.definitionQuery = "NAME = '71 IB' AND BUS_SIGNAG = 'Ferry Plaza'"

This valuable property can be utilized to reformat the ...

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